1. Field of the Invention
The present invention relates to a receiver including a two-element phased array antenna and having a capability of performing demodulation by means of multiport direct conversion.
2. Description of the Related Art
In a conventional receiver including a two-element phased array antenna, RF signals received by the two-element antenna are directly combined at the RF frequency, and demodulation is performed on the resultant combined signal.
The demodulation is performed by means of, for example, direct conversion using a mixer and a local signal.
However, the conventional receiver has the problem that because the RF signals received by the two antenna elements are directly combined at the RF frequency, information about the amplitude of each RF signal is lost. This makes it difficult for a beam former to control the directivity.
When demodulation is performed using a mixer, it is difficult to obtain a wide bandwidth and it is required to apply a high-level local signal to the mixer. The application of the high local power causes the mixer to operate in a nonlinear fashion. As a result, low-distortion demodulation becomes difficult.